Generator end winding support

ABSTRACT

Support members and spacer blocks positioned between and supporting the conductors extending beyond the magnetic core of rotating electrical machinery. The members comprise a solid insulating member having a deformed surface sandwiched between a conformable absorbent material which is impregnated with a curable resin. Upon curing of the resin, the comformable absorbent material with the solid insulating member sandwiched therebetween provides a rigid support between the conductors which is conformable to the space therebetween and which has its structural elements locked together for increased durability.

United States Patent Bishop [45] May 23, 1972 [54] GENERATOR END WINDINGSUPPORT [72] Inventor: James S. Bishop, Schenectady, NY.

[73] Assignee: General Electric Company [22] Filed: Dec. 14, 1970 211App1.No.: 97,777

[52] US. Cl.... ..310/260 [51] Int. Cl. ..II02k l/24 [58] Field ofSearch ..310/270, 260, 269, 245, 231

[56] References Cited UNITED STATES PATENTS 3,293,472 12/ 1966 Stevens..310/260 3,344,296 9/1967 Coggeshall. ....3 10/260 2,565,139 8/1951Lessmanm. ....3l0/271 2,994,735 8/1961 Marshall; ..310/260 FOREIGNPATENTS OR APPLICATIONS 1,366,320 6/1964 France ..310/260 PrimaryExaminer-J. D. Miller Assistant Examiner-R. Skudy Attorney-William C.Crutcher, Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman [57]ABSTRACT Support members and spacer blocks positioned between andsupporting the conductors extending beyond the magnetic core of rotatingelectrical machinery. The members comprise a solid insulating memberhaving a deformed surface sandwiched between a conformable absorbentmaterial which is impregnated with a curable resin. Upon curing of theresin, the comformable absorbent material with the solid insulatingmember sandwiched therebetween provides a rigid support between theconductors which is conformable to the space therebetween and which hasits structural elements locked together for increased durability.

2 Clairm, 3 Drawing figures PATENTEUMAY 23 I972 INVENTORZ JAMES BISHOP,BY W HIS ATTORNEY.

BACKGROUND OF THE INVENTION The invention relates generally tosupporting and blocking structures, and more particularly to improvedstructures for the rigid support or blocking of spaced conductor memberswhich are subject to forces tending to distort them and which are soarranged as to leave little room for elaborate support structure.

One environment for the use of this improved support is in electricalapparatus such as dynamoelectric machines or generators of highcapacity. In the stator or armature windings of a generator there arehigh currents producing powerful magnetic fields which exert a force onany conductor in the magnetic field which has a current passing throughit. The windings of a stator of a large generator carry high currentsand are subject to strong magnetic forces. The windings in the body ofthe stator are held firmly within the stator slots by wedges and maywithstand the strong forces without movement or adverse effect. However,the end portions of these windings which extend outside of the statorbody present support problems.

The end turns of a dynamoelectric machine stator are the projectingportion of the armature bars which extend outwardly from longitudinalstator slots. The end turns are necessary in order to reverse thedirection of the armature current flow through the stator assembly andto circumferentially displace a portion of the bar so that it can entera slot approximately 150, for a two-pole dynamoelectric machine, fromthe slot from which it emerged. The end turns must also diverge radiallyfrom the stator axis in order that they will not obstruct the rotor ofthe dynamoelectric machine which is turning in the stator bore.Consequently, the stator end turns assume a rather complicatedconfiguration in that they are skewed with respect to the stator axisand lie generally tangentially about a frusto-conical surface ofrevolution concentric with the stator axis. When there are two separatearmature bars in each slot, these being known as top or radially inner,and bottom or radially outer bars, one practice is to bend the top barsso that they lie tangentially in one direction about this frusto-conicalsurface and to bend the bottom bars in the opposite tangential directionabout a surface of revolution. Furthermore, although the top and bottombars are closely adjacent at the location where they emerge from theslot, they must spread radially with respect to one another as they moveaway from the stator so that space will be afforded for a series loopconnecting a top bar to a bottom bar. A suitable structure forsupporting the insulated armature bars in the end turn region mustafford a rigid support to counteract magnetic forces acting on theconductor bars. The support structure should be composed of as few partsas possible with all of the parts keyed or doweled together. Also, theparts or materials used should be non-abrasive and should be capable ofconforming to the shape of the conductor bars so that no voids orclearances are formed between the support structures and the conductorbars. Preferably, the materials used to produce the conforming part ofthe support structure should be curable or hardenable at roomtemperature to avoid requirements of baking the whole generator andsupport structure in an oven. Furthermore, the support structure ispreferably made of a dielectric material so as not to give rise toundesirable eddy currents or short circuits.

DESCRIPTION OF THE PRIOR ART Previous support structures have includedthe use of resin impregnated fabric materials mounted between conductorbars to conform to the shape therebetween, and in one instance to theuse of a pad of compressible absorbent material sandwiched between tworelatively solid insulating members forced between conductor bars inorder to provide blocking support therebetween. The pad of compressibleabsorbent material sandwiched between the two relatively solidinsulating members in the prior art was impregnated with athermosettable resin composition which hardened at room temperature.However, such prior art structure did not provide means to prevent theabsorbent material from becoming detached from the solid insulatingmembers should there be shrinkage or relative movements of the parts.

SUMMARY OF THE INVENTION Briefly stated, the essence of this inventionis a spacer block or support structure which comprises the use of amember of conformable absorbent material impregnated with a hardenableresin disposed between a deformed surface of a rigid or solid member anda conductor bar to be supported. The member therefore forms a rigidspacer block or support for the conductor bars in which no voids areformed between the support structure and the conductor bars although theshape of the conductor bars may vary. The elements are locked togetherby means of the conformable absorbent material hardening to a shapewhich complements that of the deformation formed in the solid member.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter which is regarded as the invention, it is believed that theinvention will be better understood from the following description takenin connection with the accompanying drawings in which:

FIG. 1 is an elevation view partly in section showing the support systemof this invention at one end of a generator stator,

FIG. 2 is a top view partly in section showing the support structure ofthis invention as used in a portion of the end turn region of thearmature bars of FIG. 1, and

FIG. 3 is a cross sectional view of the invention taken along line 3-3of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now, moreparticularly, to FIG. 1 to illustrate the principles of the invention,there is shown an elevation view of a portion of a generator in whichthe invention may be used. There is shown a stator core assembly 10 witha rotor assembly 11 mounted to rotate within the stator core assembly10. Extending from the stator core assembly 10 is the radially inner ortop armature stator conductor bar 12 and radially outer or bottomconductor bar 13. These conductor bars 12 and 13 are bent radiallyoutward as they leave the stator slots in order to accommodate the endsupporting structure and to provide suflicient room for the rotorassembly 11. Furthermore, the inner or top bars are bent in onecircumferential direction and the outer or bottom bars are bent in theother circumferential direction, not shown, so that each inner bar maybe joined by a series loop with an outer bar emanating from a statorslot located apart on the stator assembly circumference. In other words,an inner bar on one side of the stator circumference is connected withan outer bar diametrically opposite by a series loop. Each of theseinner bars 12 and outer bars 13 must be rigidly supported to preventmovement due to the magnetic forces operating on them and must besufficiently insulated from adjacent conductor bars.

There is shown in FIG. 1 a support member 14 which is rigidly mountedpreferably to the stator core 10 by means well known in the art such asbracket 9. The support member 14 completes a full circle about thestator core 10 forming a frusto-conical surface upon which rings 15, 16and 17 are mounted. The rings 15, 16 and 17 may be made of reinforcedglass or any other suitable fairly rigid material, and may alsopreferably be made of an insulative material. The rings, if notperfectly manufactured, may be shimmed by any suitable shim material asshown at 18 in order to properly mount the rings 15, 16 and 17 onsupport member 14. A conformable absorbent material 19 impregnated witha resin which will cure at room temperature is mounted between adeformed surface or notch 40 on the inner circumferential surface ofglass ring 15 and the bottom or outer radial stator bar 13. Similarly,conformable absorbent materials 20, 21 impregnated with resin are placedin similar notches in rings 16, 17. Any suitable conformable absorbentmaterial such as a felt or woven body of an absorbent fibrous materialsuch as glass or preferably an organic fiber manufactured by DuPontunder the trademark Dacron may be used as the conformable absorbentmaterial 19.

The conformable absorbent material may be impregnated with any suitablethermosetting resin which hardens upon curing, but preferably a resin isselected which will cure at room temperature and which does not requirebaking to harden. A number of well-known commercially availablesolventless thermosetting resins may be used in the practice of thisinvention, particularly those therrnosetting resins that will harden atroom temperature. The therrnosetting resins that may be used include butnot limited to polyester resins and epoxy resins. When the conformablematerial resin is cured, it becomes rigid and the deformed surface ornotch 40 thereby prevents relative movements between members.

A similar process is carried out in forming the support structurebetween the lower conductor bars 13 and upper conductor bars 12.However, the space for the radial support structure between the upperconductor bars 12 and the lower conv ductor bars 13 and which is nearestthe stator core assembly may be insufficient to allow the use of a rigidor solid insulating ring. Therefore a support structure 22 may be formedfrom a strip of conformable absorbent material impregnated with a roomtemperature curable resin omitting the use of a rigid ring. The supportstructures between the lower conductor bars 13 and the upper conductorbars 12 in the two positions furthest removed from the stator coreassembly 10 use rings of a suitable rigid material having deformed innerand outer circumferential surfaces such as shown at 23 and 24. Theserings 23 and 24 are inserted between the upper stator conductor bars 12and lower stator conductor bars 13, and a conformable resin impregnatedmaterial such as Dacron impregnated with a room temperature curableresin is inserted as shown at25, 26, 27 and 28. The stator bars 12 and13 are then bound together by glass or other suitable roving material asshown at 29, 30 and 31 to provide a rugged support structure in theradial direction.

Referring now more particularly to FIG. 2, there is shown a top view ofa set of three inner radial or top stator conductor bars 12. It is to beunderstood that FIG. 2 would be equally applicable to a description ofthe support structure between the outer radial or bottom statorconductor bars 13 since the support structure between the bottom statorconductor bars 13 would be identical. A tension member 32 is shownbinding together a number of top stator bars 12. The tension member 32is made in two parts, an upper and lower half or part, which arefastened together by pin means in order to facilitate the assembly ofthe support structure. A suitable construction and method for attachingthe tension members 32 is disclosed in US. Pat. No. 3,135,888 issued toA. D. Coggeshall on.June 2, 1964 and incorporated by reference herein.

Also shown in FIG. 2, through cut out sections of tension member 32, areblocking members 33 and 34 between the top stator conductor bars 12.These blocking members 33 and 34 are identical and will therefore bediscussed only in terms of spacer block 33. The block 33 includes acentral member of any suitable rigid or solid material 35 and may bepreferably a cotton polyester laminate such as one manufactured by theGeneral Electric Company under the trademark of Textolite. The solid orrigid material 35 is sandwiched between Dacron felt or any othersuitable conformable absorbent material impregnated with a roomtemperature curable resin as shown at 36 and 37.

In FIG. 3 there is shown a cross sectional view taken along line 3-3 ofFIG. 2 in which there is shown three top stator conductor bars 12,tension member 32 and spacer blocks 33 and 34. As shown in FIG. 3, therigid solid material 35 has a notch or fish hook 38 formed in at leastone surface so that upon hardening of the resin in the conformableabsorbent material 37, the parts or elements of the block will be lockedtogether against relative movements. A convenient method of assembly ofthe block components between the top bars may be described in terms ofblock 33 since block 34 is identical to the block 33. As mentionedsupra, the lower half of the tension member 32 is mounted under theconductor bars 12 prior to placing the resin impregnated material 22, 25and 27 in position. A U shaped conformable absorbent material 37 isinserted between a pair of top stator conductor bars 12 after beingimpregnated with a resin curable at room temperature. However, it isequally feasible to mount the conformable absorbent material 37 in a U"shape between the top stator conductor bars 12, and then, afterassembly, to spray the material 37 with a curable resin. The rigidmember 35 with a fish hook or other suitable depression or surfacedeformation 38 is then forced into the center of the U shapedconformable material 37. The remaining blocking members such as 34 areassembled in similar fashion. The tension member 32 is then used toplace the assembly under tension according to the aforementionedCoggeshall patent, and the support structure assembly is then left tostand for a suitable period of time until the resin hardens.

An alternate method of application consists of applying a long strip ofabsorbent material across several spaces to be blocked, and theninserting several rigid members in sequence, so that each rigid memberforms a U" shaped cavity by wedging action. The remainder of theoperation is the same as before.

It is to be appreciated that an important aspect of the invention is theuse of a conformable material in conjunction with a rigid materialwherein the conformable material is placed in contact with the conductorbars which may not all be shaped identically and therefore will providecomplete contact between the support structure and the conductor bars toprovide a stronger and more durable support structure. Another aspect ofthe invention which is equally important is that the conformablematerial which is impregnated with a hardenable resin and the rigidsupport member may be locked in position by means of a fish hook, notchwith a barb, or other suitable deformation in the surface of the rigidmember thereby forming a rigid support structure better adapted towithstand the forces acting against the support structure over longperiods of time and to resist deterioration of the support structure dueto constant vibration over long periods of time.

It will be apparent to those skilled in the art that the blocking andsupport structure described herein may be used to space or to supportconductors in any apparatus in which the spacing of the conductorsprovide little room for a sturdy support structure. It is also apparentthat various changes and modifications may be made in the structure, ordifferent materials used to produce the same result in the structure.For example, a proturberance on the rigid member which is sandwichedbetween the conformable absorbent material could be used in place of thenotch or depression used to lock the elements of the support structuretogether.

In view of the above, it will be apparent that modifications andvariations are possible within the scope and spirit of the aboveteachings. It therefore is to be understood that within the scope of theappended claims the invention may be practiced other than asspecifically described.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A support for spaced conductor bars, comprising:

a substantially U" shaped member of conformable absorbent materialimpregnated with a hardenable resin cured to a rigid state, saidsubstantially U" shaped member of conformable absorbent material beingdisposed between a pair of spaced conductor bars, and

a member of rigid material being mounted within said sub stantially Ushaped member to provide support between the spaced conductor bars, saidmember of rigid material being provided with a surface having adeformation in order to lock said substantially U shaped member ofconformable absorbent material and said rigid member in position. 2. Asupport for spaced conductor bars as recited in claim 1 wherein saiddeformation in said surface of said rigid member is a notch with a barboriented to prevent withdrawal of said 5 rigid member from said U"shaped member.

* 'l l l

2. A support for spaced conductor bars as recited in claim 1 whereinsaid deformation in said surface of said rigid member is a notch with abarb oriented to prevent withdrawal of said rigid member from said''''U'''' shaped member.